/*
 * Copyright (c) 2020 Particle Industries, Inc.  All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation, either
 * version 3 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */

#pragma once

#include <atomic>
#include <mutex>

namespace particle {

template <typename R, R(*spin)()>
class AtomicFlagMutex {
    std::atomic_flag flag = ATOMIC_FLAG_INIT;
public:
    void lock() {
        while (flag.test_and_set(std::memory_order_acquire)) {
            spin();
        }
    }

    void unlock() {
        flag.clear(std::memory_order_release);
    }
};

class SimpleAtomicFlagMutex {
    std::atomic_flag flag = ATOMIC_FLAG_INIT;
public:
    void lock() {
        while (flag.test_and_set(std::memory_order_acquire)) {
        }
    }

    void unlock() {
        flag.clear(std::memory_order_release);
    }
};

} // namespace particle
